194 FRACTIONAL EXCRETION OF MAGNESIUM AND RENAL FUNCTION IN CYSTIC FIBROSIS C MUNRO1,2, S RANGANATHAN1,2, C QUINLAN1,2 1The

Royal Children’s Hospital, Melbourne, Victoria; 2The Murdoch Children’s Research Institute, Melbourne, Victoria, Australia Aim: To assess the fractional excretion and renal function of children with Cystic Fibrosis (CF). Background: Patients with CF are at risk of magnesium deficiency due to: gastrointestinal losses, renal losses, and drugs causing magnesium wasting. The prevalence is suggested to be 3% and it is less frequently reported in children than in adults. We sought to examine FeMg in subjects with CF during

treatment with aminoglycosides. Methods: Patients aged ≤ 6 years were recruited when commencing IV aminoglycosides and Erlotinib in vivo have urinary and serum sampling of creatinine and magnesium on days 1, 4, 5, 7 and 10–14. Estimated glomerular filtration rate (eGFR) was calculated using the Zapitelli, Bouvet and Schwartz CKiD formulae. FEMg was calculated as: Results: 6 patients, aged 0.53–6.87 years, 3 males, 3 gentamicin and 3 tobramycin, have been recruited to date. A total of 44 patients will be recruited. Mean eGFR (± SD) was 102.7 (± 11.3) mL/min/1.73 m2 by the Zapitelli formula, 59 (± 21.9) mL/min/m2 by the Bouvet and 107 (± 16.3) enough mL/min/1.73 m2

by Schwartz. FEMg was PD-0332991 clinical trial considered elevated if >1.4%. Mean (± SD) FEMg on day 1 was 3.95 (± 2.78)%, rising to 9.3 (± 2.35)% on day 5 and dropping back to 3.64 (± 1.66)% by day 10–14. Conclusions: Aminoglycosides are widely used in CF and are introduced at a younger age, as more children are diagnosed following newborn screening. There are concerns that aminoglycosides contribute to renal disease in patients with CF. The effect of aminoglycosides on FEMg has not previously been studied. The proposed action of Mg in CF is incompletely understood. These results suggest that the metabolism and excretion of Mg in CF warrants further study, and that aminoglycosides considerable alters Mg excretion. 195 HETEROZYGOUS LMX1B MUTATION DETECTION IN FAMILIAL FSGS WITHOUT EXTRARENAL MANIFESTATIONS USING WHOLE EXOME SEQUENCING J FLETCHER1, A MALLETT2,3, G HO4, H MCCARTHY5, A SAWYER6, A MALLAWAARACHCHI7, M ROSIER1, M LITTLE8, B BENNETTS4, H JUPPNER9, A TURNER10, SI ALEXANDER5 1Department of Paediatrics, The Canberra Hospital, Australian Capital Territory; 2Department of Renal Medicine, Royal Brisbane and Women’s Hospital, Queensland; 3CKD.